uncertainty. So the PN [3] takes into account continual change in the shear area but prescribes to carry out at least
5 particular tests (5 values of the normal stress). The differences in values of shear strength parameters obtained
with and without taking into account continual change in the shear area are relatively high (up to 13.1% for angle of
internal friction). From the reason that it is proposed linear relationship between normal and shear stress, increase in
values of angle of internal friction cause decrease in values of cohesion (see 2 last columns in the Tab. 4). We
would like to note that when carried out only 3 particular tests (possible e. g. by [4], [5], [6], [7] and [8]); taking into
account continual change in the shear area can provide inadequate high values of shear strength parameters.